System and method for positioning an optical preform in a furnace

ABSTRACT

A system for positioning an optical preform in a furnace is provided that includes an upper muffle and a downfeed handle assembly with a tube defining a first end and a second end, the second end extending into the upper muffle. A handle is disposed within the tube. A second end of the handle extends into the upper muffle and a seal assembly is positioned around both the tube and the handle. The first end of the handle extends through the seal assembly and a drive assembly is coupled with the downfeed handle.

This application is a divisional and claims the benefit of priorityunder 35 U.S.C. § 120 of U.S. patent application Ser. No. 15/657,329,filed on Jul. 24, 2017, which claims the benefit of priority under 35U.S.C. § 119 of U.S. Provisional Application Ser. No. 62/368,581 filedon Jul. 29, 2016 the content of which is relied upon and incorporatedherein by reference in its entirety.

FIELD OF THE DISCLOSURE

The present disclosure generally relates to a system for positioning anoptical component, and more particularly, to a system for positioning anoptical preform within a furnace.

BACKGROUND

Furnaces used in the production of optical fibers and consolidation ofoptical fiber preforms typically require isolated environments suppliedby various sealing methodologies and employ controlled flow of one ormore non-reactive or noble gases in the production of optical fibers andthe consolidation of optical fiber preforms. Seals within and proximateto the furnace may be exposed to high heat, necessitating the use ofhydrostatic seals or high temperature tolerant materials. Use ofhydrostatic seals may allow for the uncontrolled escape of thenon-reactive or noble gases from the system resulting in added cost andloss of a non-renewable resource.

SUMMARY OF THE DISCLOSURE

According to at least one aspect of the present disclosure, a system forpositioning an optical preform in a furnace is provided that includes anupper muffle and a downfeed handle assembly with a tube defining a firstend and a second end, the second end extending into the upper muffle. Ahandle is disposed within the tube. A second end of the handle extendsinto the upper muffle and a seal assembly is positioned around both thetube and the handle. The handle extends through the seal assembly. Adrive assembly is coupled with the handle.

According to another aspect of the present disclosure, a method forpositioning an optical preform in a furnace is provided that includessteps of providing a chuck interface movably coupled with a driveassembly; positioning the chuck interface within a seal assembly;coupling a handle within the chuck interface, an optical fiber preformpositioned on an opposite end of the handle from the chuck interface;positioning the handle within a tube; positioning the optical fiberpreform within a furnace; and moving the handle at least one oflaterally and rotationally within the tube such that the optical fiberpreform is moved at least one of laterally and rotationally within thefurnace.

According to another aspect of the present disclosure, a system forpositioning an optical preform in a furnace is provided that includes adownfeed handle with a tube defining a first end and a second end. Ahandle is disposed within and extends through the tube and a sealassembly extends around both the handle and the tube. The handle extendsthrough the seal assembly. The tube terminates within the seal assembly.A chuck interface is positioned around the handle and within the sealassembly. A drive assembly has a chuck. The chuck is configured toaccept the chuck interface. The drive assembly is configured to move thechuck interface within the seal assembly and the handle within the tube.

These and other features, advantages, and objects of the presentdisclosure will be further understood and appreciated by those skilledin the art by reference to the following specification, claims, andappended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 depicts a schematic cross-sectional view of a preformconsolidation system incorporating a seal assembly, according to oneembodiment;

FIG. 2 depicts an enhanced view of the seal assembly of FIG. 1,according to one embodiment; and

FIG. 3 depicts a method of positioning an optical fiber preform within afurnace; according to one embodiment.

DETAILED DESCRIPTION

Additional features and advantages of the disclosure will be set forthin the detailed description which follows and will be apparent to thoseskilled in the art from the description, or recognized by practicing theinvention as described in the following description, together with theclaims and appended drawings.

As used herein, the term “and/or,” when used in a list of two or moreitems, means that any one of the listed items can be employed by itself,or any combination of two or more of the listed items can be employed.For example, if a composition is described as containing components A,B, and/or C, the composition can contain A alone; B alone; C alone; Aand B in combination; A and C in combination; B and C in combination; orA, B, and C in combination.

In this document, relational terms, such as first and second, top andbottom, and the like, are used solely to distinguish one entity oraction from another entity or action, without necessarily requiring orimplying any actual such relationship or order between such entities oractions. The terms “comprises,” “comprising,” or any other variationthereof, are intended to cover a non-exclusive inclusion, such that aprocess, method, article, or apparatus that comprises a list of elementsdoes not include only those elements but may include other elements notexpressly listed or inherent to such process, method, article, orapparatus. An element preceded by “comprises . . . a” does not, withoutmore constraints, preclude the existence of additional identicalelements in the process, method, article, or apparatus that comprisesthe element.

Referring to FIG. 1, reference numeral 10 generally designates a preformconsolidation system configured to consolidate an optical fiber preform.The preform consolidation system 10 includes a downfeed handle 12 whichis movable within the preform consolidation system 10. The downfeedhandle 12 includes a handle 14 disposed within a tube 18. The handle 14may include a first end 14A and a second end 14B positioned at oppositeends of the handle 14. The first end 14A is a top end and the second end14B is a bottom end. The handle 14 may be composed of a glass, glassceramic or ceramic material. In a specific example, the handle 14 may becomposed of quartz. The tube 18 may define a first end 18A and a secondend 18B. In the depicted example, the first end is a top end and thesecond end 18B is a bottom end. Further, the tube 18 is hollow such thatan inner volume 18C is defined within the tube 18. The handle 14 passesthrough the inner volume 18C of the tube 18. The tube 18 has a greaterinternal diameter than an external diameter of the handle 14 such thatthe handle 14 may move horizontally within the inner volume 18C of thetube 18 independently of the tube 18. The tube 18 may be composed of aglass, glass ceramic or ceramic material. In a specific example, theouter tube 18 may be composed of quartz or silica glass, but is notlimited thereto. According to various examples, the handle 14 may extendout of the first and second ends 18A, 18B of the tube 18.

The preform consolidation system 10 further includes a seal assembly 22.The seal assembly 22 is configured to minimize or prevent theuncontrolled escape of gases from within the preform consolidationsystem 10 and prevent gases present in an environment around the system10 from entering the preform consolidation system 10. The seal assembly22 is positioned around both the handle 14 and the tube 18. The handle14 may extend fully through the seal assembly 22 and the tube 18. Thetube 18 may terminate within the seal assembly 22 (i.e., the first end18A of the tube 18 is surrounded by the seal assembly 22). As will beexplained in greater detail below, use of the seal assembly 22 allowsthe handle 14 to be movable in a lateral, or X-Y, horizontal direction,as well as rotate about a Z-direction within the tube 18 whileminimizing or preventing the escape of gases from the top of the preformconsolidation system 10. An outside diameter of the handle 14 and anoutside diameter of tube 18 are sized such that a desired extent oflateral motion for handle 14 relative to the tube 18 can be achieved.This difference in diameter between the handle 14 and the tube 18 isequivalent to the difference between the diameter of a preform 50 and anupper muffle 42 (e.g., less than about 0.5 inches, less than about 0.25inches, or less than about 0.125 inches).

Positioned around the tube 18, and below the seal assembly 22, is a tophat 26. Positioned at an interface between the top hat 26 and the tube18 is a seal 30. In one example, the seal 30 may be a lip seal. The seal30 is configured to allow sliding motion of the tube 18 in and out of,or through, the top hat 26 in a vertical, or Z-direction, whilemaintaining a seal to prevent the escape of gases within the preformconsolidation system 10. The seal 30 may be a radial shaft seal composedof an elastomeric material. According to one example, the seal 30 may bea spring energized plastic u-cup seal. In such an embodiment, the springmay provide the restoring force against the self-restoring aspect ofelastomer materials. According to various examples, the seal 30 mayexhibit a low coefficient of friction. The handle 14 and seal assembly22 may similarly move in the vertical direction with the tube 18 suchthat the seal assembly 22 may move towards, or away from, the top hat26. The top hat 26 extends over, and is positioned above, a gas passage34. The gas passage 34 may be a single opening or a plurality ofopenings to allow controlled and directed flow of gas. Positionedbetween the top hat 26 and the gas passage 34 is a top hat seal 38.According to various examples, the top hat seal 38 may be an inflatableseal as explained in greater detail below. The top hat seal 38 isconfigured to prevent the interchange of gases within the preformconsolidation system 10 and the environment. The top hat seal 38 may becomposed of an elastomeric material within an inner gas void which mayfunction as a bladder. As a pressure within the inner gas void isincreased, the elastomeric material of the top hat seal 38 may increasein size thereby sealing the top hat 26 to the gas passage 34. The tophat seal 38 may be positioned on the gas passage 34, the upper muffle 42or an inner surface of the top hat 26. According to various examples,the top hat 26, the gas passage 34, and/or the top hat seal 38 mayinclude a passageway configured to pass coolant (e.g., water) such thatthe top hat seal 38 may not overheat.

The top gas passage 34 may be a cylindrical, double wall mechanicaldevice with flanges at both ends for mounting that may be used tosupply, for example, inert gas to a furnace portion of the preformconsolidation system 10. Fluidly coupled with the gas passage 34 is anupper muffle 42. The upper muffle 42 defines an inner passageway 46through which a fiber preform 50 may pass. The fiber preform 50 issupported by the second end 14B of the handle 14. Specifically, a fusedsilica glass boule 52 is coupled to the second end 14B of the handle 14and configured to hold an end of the fiber preform 50. Positionedbetween the boule 52 and the handle 14 is a baffle 54. The baffle 54 maybe joined to the boule 52 through a glass join seal. The baffle 54 issized and positioned on the second end 14B of the handle 14 to resistthe interchange of gases (e.g., minimize fluid communication) betweenthe inner passageway 46 and the inner volume 18C. The baffle 54 may havea wider diameter than the tube 18. The baffle 54 may be composed ofquartz. Positioned on an outer surface of the tube 18 at the second end18B is a flange 56. The flange 56 is sized and configured to contact thetop hat 26 proximate the seal 30. A gap is maintained between the topsurface of the baffle 54 and the bottom of flange 56 to insure handle 14can move relative to the tube 18. This gap may be less than about 0.125inches, less than about 0.09375 inches, or less than about 0.0625inches. The flange 56 may be advantageously used to hold the top hat 26when the downfeed handle 12 is pulled away from the preformconsolidation system 10 (e.g., for example when loading a new fiberpreform 50 into the preform consolidation system 10). As the fiberpreform 50 is lowered into the upper muffle 42, the top hat 26 will beheld by the flange 56, and will set down onto the gas passage 34 atwhich point the downfeed handle 12 will continue lowering the fiberpreform 50 into the preform consolidation system 10.

Positioned below the upper muffle 42 is a furnace 58. The furnace 58 isconfigured to apply heat to the fiber preform 50 such that the fiberpreform 50 may be consolidated (e.g., increased in density). The furnace58 may be heated to a temperature of about 1500° C.

Referring now to FIG. 2, as explained above, the handle 14 extendsthrough the seal assembly 22. Positioned above the seal assembly 22 is adrive assembly 74. The drive assembly 74 includes a chuck 78 which iscoupled to the handle 14 through a chuck interface 82. The driveassembly 74 may include two linear stages, stacked vertically, andattached 90° apart. The drive assembly 74 is configured to providemovement in an X- and Y-direction (e.g., lateral movement) to the handle14 within the tube 18 (i.e., and therefore the optical fiber preform 50within the furnace 58). Further, the chuck 78 may be rotated via arotational drive coupled to the two linear stages, thereby allowing thehandle 14 and optical fiber preform 50 to be rotated independently ofthe tube 18, the seal assembly 22 and furnace 58. In rotationalembodiments, the tube 18 and/or seal assembly 22 may be rotationallylocked. According to various examples, the chuck 78 may include aplurality of jaws 86 configured to grip the chuck interface 82. In thedepicted example, the chuck 78 includes three jaws 86 (i.e., with onlyone being visible in the depicted cross-sectional view) configured togrip around the chuck interface 82, but may have less than, or morethan, three jaws 86. It will be understood that the chuck 78 may notinclude the jaws 86, but may incorporate other gripping structures(e.g., clamps, fasteners, etc.) without departing from the teachingsprovided herein.

The chuck interface 82 is configured to couple the drive assembly 74 andthe jaws 86 to the first end 14A (FIG. 1) of the handle 14. The chuckinterface 82 defines an interface body 90 and an interface flange 94.The interface body 90 is configured to be gripped by the jaws 86. Thechuck interface 82 defines an aperture 98 into which the first end 14Aof the handle 14 is positioned. The aperture 98 extends through theinterface flange 94 and the interface body 90. An inner handle seal 102is positioned within the aperture 98 between the interface body 90 andthe handle 14. The interface flange 94 extends radially outward from theinterface body 90. The interface flange 94 may extend around theinterface body 90 equally (e.g., in a circular shape) or in other shapesand configurations that may be contemplated. The interface flange 94defines a flange face 106 which is configured to couple with the sealassembly 22 as explained in greater detail below. Positioned on top ofthe chuck interface 82 is a handle lock 108. The handle lock 108 definesa handle flange 110 configured to engage a handle groove 112 defined bythe handle 14. Engagement of the handle flange 110 with the handlegroove 112 provides support to the handle 14 such that the handle 14 maymove in the Z-direction with the seal assembly 22. The weight of thehandle 14 is transferred to the chuck interface 82 through the handlelock 108 being positioned on top of the chuck interface 82.

The seal assembly 22 is configured to accept the chuck interface 82, thehandle 14 and the tube 18 while preventing the escape of gases fromwithin the preform consolidation system 10. The seal assembly 22includes a top plate 114, a seal body 118 and a bottom plate 122. Thetop plate 114 defines a chuck aperture 126 configured to accept thechuck interface 82. The chuck aperture 126 may a have a greater diameterthan the interface body 90 such that the chuck interface 82 may movewithin, and relative to, the seal assembly 22 in a lateral (e.g., X- andY-) direction. Defined between the top plate 114 and the seal body 118is a flange opening 130. The flange opening 130 is sized to accept theinterface flange 94 and to allow lateral movement of the interfaceflange 94 (i.e., and the chuck interface 82) in a horizontal planerelative to the seal assembly 22. The seal body 118 defines a sealaperture 134 connecting the flange opening 130 and a tube opening 138.Positioned around the seal aperture 134 is a face seal 142. The faceseal 142 is configured to physically contact the flange face 106. Theface seal 142 and the flange face 106 are configured to provide a sealedcoupling to prevent gases within the preform consolidation system 10from escaping. The face seal 142 is configured to contact the flangeface 106 such that the interface flange 94 may be moved within the sealassembly 22 while preventing gases from escaping from within the innervolume 18C of the tube 18 (i.e., and thereby the furnace 58 (FIG. 1)).Movement of the flange face 106 across the face seal 142 allows for thetranslational movement of the handle 14 within the tube 18. Rotationalmovement of the chuck 78 allows for rotational movement of the flangeface 106 across the face seal 142 and concomitant rotational movement ofthe handle 14 within the tube 18. According to various examples, theface seal 142 may be composed of an elastomeric material. In anotherexample, the face seal 142 may be composed of a glass filled Teflon. Theface seal 142 may be of sufficiently low friction (e.g., a staticcoefficient of friction of between about 0.05 and about 0.2) to minimizeangular deflection within the handle 14 as the handle 14 is moved withinthe tube 18 by the drive assembly 74. The depicted example of thedownfeed handle 12 minimizes the moment load applied to the handle 14during horizontal movement by locating the face seal 142 in closeproximity to the drive assembly 74. This allows the face seal 142 to belocated at a free end (e.g., the first end of handle 14 of the downfeedhandle 12).

The first end 18A (FIG. 1) of the tube 18 is positioned within the tubeopening 138 of the seal assembly 22. The seal assembly 22 includes atube seal 146 disposed within the tube opening 138 between the tube 18and the seal body 118. The tube seal 146 is configured to prevent theexchange of gases between the inner volume 18C of the tube 18 and theenvironment. The tube seal 146 may be composed of an elastomericcomponent. The bottom plate 122 defines a tube lock 150. The tube lock150 is configured to engage a tube groove 154. Engagement of the tubelock 150 with the tube groove 154 allows the seal assembly 22 to supportthe tube 18 such that the tube 18 is movable in the Z-direction with theseal assembly 22.

Referring now to FIGS. 1 and 2, according to one exemplary method ofoperating the downfeed handle 12 within the preform consolidation system10, the downfeed handle 12 and the top hat 26 are positioned above theupper muffle 42 and gas passage 34 in a spaced apart configuration. Thetop hat 26 is supported by the tube 18 at the flange 56. The fiberpreform 50 is loaded into the boule 52 and then lowered into the uppermuffle 42. As the fiber preform 50 is lowered into the upper muffle 42and into the furnace 58, the top hat 26 comes to rest around the top ofthe gas passage 34. Positioned below the furnace 58 is a gas port 36configured to allow gas to enter and exit the preform consolidationsystem 10. It will be understood that the gas passage 34 may be part ofthe upper muffle 42. Once the top hat 26 seats onto the top of the gaspassage 34, the top hat seal 38 is inflated to seal the top hat 26 tothe upper muffle 42 by pressurizing its internal void until it contactsand seals the top hat 26 to the gas passage 34. The fiber preform 50 canthen be lowered further into the furnace 58, with the downfeed handle 12sliding through the low friction seal 30. Under various circumstances,consolidation of the optical fiber preform 50 may benefit from centering(e.g., moving laterally or rotating) of the fiber preform 50 within thefurnace 58. Under such circumstances, the fiber preform 50 may be movedlaterally or horizontally within the furnace 58 by actuating the driveassembly 74 to move the handle 14 to which the preform 50 is supported.After the fiber preform 50 is consolidated, the downfeed handle 12 andthe top hat 26 may be removed from the upper muffle 42 and the furnace58 and a new fiber preform 50 may be attached to the boule 52 and theprocess restarted.

Referring now to FIG. 3, depicted is a method 160 for positioning theoptical fiber preform 50 in the furnace 58. The method 160 includessteps 164, 168, 172, 176, 180 and 184. First, step 164 of providing thechuck interface 82 movably coupled with the drive assembly 74 isperformed. As explained above, the chuck interface 82 may be movablycoupled with drive assembly 74 through the jaws 86. Next, step 168 ofpositioning the chuck interface 82 within the seal assembly 22 isperformed. Next, step 172 of coupling the handle 14 within the chuckinterface 82 is performed. As explained above, the optical fiber preform50 may be positioned on an opposite end of the handle 14 from the chuckinterface 82. Next, step 176 of positioning the handle 14 within thetube 18 is performed. Next, step 180 of positioning the optical fiberpreform 50 within the furnace 58 is performed. Finally, step 184 ofmoving the handle 14 at least one of laterally and rotationally withinthe tube 18 such that the optical fiber preform 50 is moved at least oneof laterally and rotationally within the furnace 58 is performed. Itwill be understood that although the method 160 is depicted anddescribed in a particular order, the steps 164, 168, 172, 176, 180 and184 may be performed in any order and with intervening steps.

Use of the preform consolidation system 10 of the present disclosure mayoffer several advantages. First, use of the handle 14, seal assembly 22and the tube 18 allow X-, Y- and Z-direction positioning and rotation offiber preform 50 within the furnace 58 to optimize heating of thepreform 50. As explained above, the drive assembly 74 may providelateral motion (e.g., in the X- and Y-directions) to the chuck interface82 such that the handle 14 may be moved within the tube 18 and theoptical fiber preform 50 within the furnace 58. In this way, centeringof the fiber preform 50 within the furnace 58 can be maintainedindependent of the vertical position of the preform 50. Further, asexplained above, the use of the drive assembly 74 with the handle 14,seal assembly 22 and the tube 18 allow rotation of the handle 14 and theoptical fiber preform 50 independently of the tube 18 and the furnace58. Rotation of the optical fiber preform 50 within the furnace 58 maybe advantageous in allowing uniform heating and consolidation of theoptical fiber preform 50. Second, use of the chuck interface 82, thedrive assembly 74 and the seal assembly 22 allows for a low moment loadto be applied to the handle 14. As the handle 14 may be composed of hightemperature resistance, but low bending resistant, materials, decreasingthe moment load on the handle 14 decreases the risk of cracking andfailure of the handle 14. Third, by using the above provided disclosure,the seal assembly 22, including the face seal 142, the handle seal 102and the tube seal 146, may be positioned away from the heat of thefurnace 58. As the face seal 142, the handle seal 102 and the tube seal146 are positioned away from the heat and high temperatures of thefurnace 58, the seals 142, 102, 146 can use low temperature/low costelastomer seals. As such, furnace isolation (e.g., of gases) ismaintained using standard/simple seals composed of low cost materialsthat may not require frequent replacement. Further, the need forhydrostatic face seals (e.g., a floating plate lifted by flowing gas)may be eliminated which may aid in retention of process gases within thepreform consolidation system 10. Fourth, use of the seal assembly 22allows for the movement of the handle 14 relative to the tube 18 whileminimizing the loss of process gases to the environment.

It will be understood that although the disclosure is described inconnection with a preform consolidation system 10, according to anotherembodiment, the seal assembly 22, downfeed handle 12, handle 14, tube18, as well as similarly constructed parts, may be utilized in a fiberdraw furnace in substantially the same manner. The fiber draw furnacemay be oriented vertically, similar to the preform consolidation system10. The seal assembly 22, downfeed handle 12, handle 14, tube 18, aswell as similarly constructed parts, may be utilized to prevent theescape of process gases within the fiber draw furnace in a substantiallysimilar manner to that described in connection with the preformconsolidation system 10.

Modifications of the disclosure will occur to those skilled in the artand to those who make or use the disclosure. Therefore, it is understoodthat the embodiments shown in the drawings and described above aremerely for illustrative purposes and not intended to limit the scope ofthe disclosure, which is defined by the following claims, as interpretedaccording to the principles of patent law, including the doctrine ofequivalents.

It will be understood by one having ordinary skill in the art thatconstruction of the described disclosure, and other components, is notlimited to any specific material. Other exemplary embodiments of thedisclosure disclosed herein may be formed from a wide variety ofmaterials, unless described otherwise herein.

For purposes of this disclosure, the term “coupled” (in all of itsforms: couple, coupling, coupled, etc.) generally means the joining oftwo components (electrical or mechanical) directly or indirectly to oneanother. Such joining may be stationary in nature or movable in nature.Such joining may be achieved with the two components (electrical ormechanical) and any additional intermediate members being integrallyformed as a single unitary body with one another or with the twocomponents. Such joining may be permanent in nature, or may be removableor releasable in nature, unless otherwise stated.

It is also important to note that the construction and arrangement ofthe elements of the disclosure, as shown in the exemplary embodiments,is illustrative only. Although only a few embodiments of the presentinnovations have been described in detail in this disclosure, thoseskilled in the art who review this disclosure will readily appreciatethat many modifications are possible (e.g., variations in sizes,dimensions, structures, shapes and proportions of the various elements,values of parameters, mounting arrangements, use of materials, colors,orientations, etc.) without materially departing from the novelteachings and advantages of the subject matter recited. For example,elements shown as integrally formed may be constructed of multipleparts, or elements shown as multiple parts may be integrally formed, theoperation of the interfaces may be reversed or otherwise varied, thelength or width of the structures, and/or members, or connectors, orother elements of the system, may be varied, and the nature or numeralof adjustment positions provided between the elements may be varied. Itshould be noted that the elements and/or assemblies of the system may beconstructed from any of a wide variety of materials that providesufficient strength or durability, in any of a wide variety of colors,textures, and combinations. Accordingly, all such modifications areintended to be included within the scope of the present innovations.Other substitutions, modifications, changes, and omissions may be madein the design, operating conditions, and arrangement of the desired andother exemplary embodiments without departing from the spirit of thepresent innovations.

It will be understood that any described processes, or steps withindescribed processes, may be combined with other disclosed processes orsteps to form structures within the scope of the present disclosure. Theexemplary structures and processes disclosed herein are for illustrativepurposes and are not to be construed as limiting.

It is also to be understood that variations and modifications can bemade on the aforementioned structures and methods without departing fromthe concepts of the present disclosure, and, further, it is to beunderstood that such concepts are intended to be covered by thefollowing claims, unless these claims, by their language, expresslystate otherwise. Further, the claims, as set forth below, areincorporated into and constitute part of this Detailed Description.

What is claimed is:
 1. A method for positioning an optical preform in afurnace, comprising: providing a chuck interface movably coupled with adrive assembly; positioning the chuck interface within a seal assembly;coupling a handle within the chuck interface, an optical fiber preformpositioned on an opposite end of the handle from the chuck interface;positioning the handle within a tube; positioning the optical fiberpreform within a furnace; and moving the handle at least one oflaterally and rotationally within the tube such that the optical fiberpreform is moved at least one of laterally and rotationally within thefurnace.
 2. The method of claim 1, wherein the handle extends throughthe seal assembly.
 3. The method of claim 2, wherein the handle moveslaterally within the tube and the lateral movement of the handle isindependent of the tube.
 4. The method of claim 3, wherein the handlemoves rotationally within the tube and the rotational movement of thehandle is independent of the tube.
 5. The method of claim 1, wherein thehandle and the tube are configured to move vertically together.
 6. Themethod of claim 1, wherein the chuck interface is coupled to a face sealwithin the seal assembly.
 7. A system for positioning an optical preformin a furnace, comprising: a downfeed handle comprising: a tube defininga first end and a second end; a handle disposed within and extendingthrough the tube; and a seal assembly extending around both the handleand the tube, the handle extending through the seal assembly, whereinthe tube terminates within the seal assembly; a chuck interfacepositioned around the handle and within the seal assembly; and a driveassembly having a chuck, the chuck configured to accept the chuckinterface, wherein the drive assembly is configured to move the chuckinterface within the seal assembly and the handle within the tube. 8.The system of claim 7, wherein the handle extends fully through both theseal assembly and the tube.
 9. The system of claim 7, furthercomprising: a face seal positioned within the seal assembly and inphysical contact with the chuck interface.
 10. The system of claim 9,further comprising: a handle seal positioned around the handle withinthe chuck interface.
 11. The system of claim 10, further comprising: atube seal positioned around the tube and within the seal assembly. 12.The system of claim 11, wherein the drive assembly is configured to movethe handle at least one of laterally and rotationally within the tube.